This invention relates generally to a paper machine, and more particularly, to a system and method for predicting web break sensitivity in the paper machine and isolating machine variables affecting the predicted web break sensitivity.
A paper machine of the Fourdrinier-type typically comprises a wet-end section, a press section, and a dry-end section. At the wet-end section, the papermaking fibers are uniformly distributed onto a moving forming wire. The moving wire forms the fibers into a sheet and enables pulp furnish to drain by gravity and dewater by suction. The sheet enters the press section and is conveyed through a series of presses where additional water is removed and the web is consolidated (i.e., the fibers are forced into more intimate contact). At the dry-end section, most of the remaining water in the web is evaporated and fiber bonding develops as the paper contacts a series of steam-heated cylinders. The web is then pressed between metal rolls to reduce thickness and smooth the surface and wound onto a reel.
A problem associated with the Fourdrinier-type paper machine is that the paper web is prone to break at both the wet-end section of the machine and at the dry-end section. Web breaks at the wet-end section, which typically occur at or near the site of its center roll, occur more often than breaks at the dry-end section. Dry-end breaks are relatively better understood, while wet-end breaks are harder to explain in terms of causes and are harder to predict and/or control. Web breaks at the wet-end section can occur as much 15 times in a single day. Typically, for a fully-operational paper machine there may be as much as 35 web breaks at the wet-end section of the paper machine in a month. The average production time lost as a result of these web breaks is about 1.6 hours per day. Considering that each paper machine operates continuously 24 hours a day, 365 days a year, the downtime associated with the web breaks translates to about 6.66% of the paper machine""s annual production, which results in a significant reduction in revenue to a paper manufacturer. Therefore, there is a need to reduce the amount of web breaks occurring in the wet-end section of a paper machine.
This invention has developed a system and method for predicting a time-to-break for a paper web in either the wet-end section or the dry-end section of the paper machine. In addition, this invention is able to isolate the root cause of the predicted web break. Thus, in this invention, there is provided a plurality of sensors for obtaining a plurality of measurements from the paper machine. Each of the plurality of measurements relate to a paper machine process variable. A processor processes each of the plurality of measurements into a modified principal components data set. A break predictor, responsive to the processor, predicts a paper web time-to-break within the paper machine from the plurality of processed measurements.